Bohemian ruby red flash cut glass goblet. These glasses are known for their distinctivedeep red color, which is achieved by a process involving the addition of gold salts or copper to molten glass. The "flash" refers to a thin layer of ruby glass cased over clear glass, which is then cut to create decorative patterns, revealing the clear glass underneath and creating a striking contrast. Bohemian glass, especially cut crystal, has a rich history originating from the Bohemia and Silesia regions (now parts of the Czech Republic and Poland). Ruby glass, specifically, gained prominence in the 17th century and saw refinement in the 19th century with intricate engravings and cut patterns.